1. Field of the Invention
The present invention relates to a pressure sensor, and more particularly to a pressure sensor for determining the pressure of a medium in a hose section of an infusion conduit.
2. Description of Related Art
From European Pat. 0 291 727, a pressure sensor for measuring the pressure of a one-way pump cartridge is known. This sensor is provided with a rod-shaped pressure member set against a membrane of the pump cartridge and held by a pair of leaf springs. With a high pressure acting on the membrane, the pressure member is pushed back against the resiliency of the leaf springs. One of the leaf springs has resistance strain gauges with which the deformation of this leaf spring may be measured to determine therefrom the pressure prevailing in the pump cartridge.
Generally, measuring pressures or forces with high accuracy by means of resistance strain gauges is rather complicated and troublesome. The resistance strain gauges require extremely careful mounting. Moreover, there is a danger that a long-time drift of the measuring signal may occur due to ageing of the joints.
Other known pressure sensors detect pressures by means of a capacitive measuring of forces. Due to the fact that the dielectric constant of the dielectric changes with time in dependence on the humidity of the air, temperature or contamination, these devices also have a rather limited long-time accuracy.
It is an object of the present invention to provide a pressure sensor that is of simple construction, yet which allows highly accurate pressure measurement, the accuracy of which may be maintained even during long-time use and under varying environmental conditions.